This invention relates to a valve. It is of particular applicability to a control valve that can be used as a settable coolant flow valve or as a dispense valve for beverages, e.g. to control flow of syrups and carbonated water to a dispenser. However, it will be appreciated that the invention is not limited to valves for such uses.
Thus it is an object of the invention to provide a valve that is suitable for use as a control valve that can be maintained for a period of time in a partially open configuration or can be used in a situation where frequent opening and closing of the valve is required.
It is also an object of the invention to provide a valve which can be set with precision to any position in a desired range of partially open configurations between the fully closed and fully open positions and which can demonstrate a high degree of flow linearity between the fully closed and fully open positions.
Ingress of particles of dirt can cause problems in many valve systems. In addition to getting trapped between valve closure surfaces, where they can damage valve ports or seats, dirt particles can obstruct the cross-sectional area available for flow, and thereby alter predicted flow rates for a given valve opening. Thus it will be appreciated that this can be a particularly serious problem if a valve is particularly intended for use in a partially open, set configuration.
It is a further object, therefore, of the present invention, to provide an improved control valve in which the problems caused by dirt particles can be avoided or at least ameliorated.
Accordingly the invention provides a valve, the valve comprising a substantially rigid housing containing a passageway between an inlet and an outlet of the valve, a closure member movable in the passageway from a first position in which the valve is fully closed to a second position in which the valve is fully open, the closure member engaging the wall of the passageway to seal the passageway, the wall of the passageway or the closure member defining at least one groove, the groove having a transverse cross section that increases in area in the downstream or upstream direction, whereby movement of the closure member from the first position towards the second position opens a flow channel through the groove.
Thus it will be appreciated that flow through the valve in the partially to fully open positions is through the groove or grooves.
Preferably the closure member comprises a substantially rigid piston, which may be of the same material as the housing, e.g. of metal, plastics material or ceramic material. Suitably rigid plastics materials include, for example, acetals and acrylonitrile-butadiene-styrene (ABS) copolymers. The grooves may be, for example, cut or moulded into the material of the passageway wall or closure member by conventional means depending on the material used.
The valve may conveniently be accurately set in any desired position from fully closed to fully open by means of, for example, a lever mechanism, a stepper motor, e.g. of the pulsed magnetically driven type, a proportional solenoid activator, a diaphragm operated mechanism, or the like. When the valve is to be repeatedly opened and closed a stepper motor or proportional solenoid actuator means may be preferred. Stepper motors, for example, can provide particularly accurate incremental increases or decreases in flow control.
The closure member may carry one or more sealing rings to engage the wall of the passageway in the first position, i.e. the closure member may engage the wall of the passageway by means of the sealing ring(s) to close the outlet. Alternatively, sealing rings for this purpose may be located in the wall of the passageway. In a yet further embodiment the closure member and passageway may be a precision fit in the first position to close the outlet without a seal.
Accordingly, in one specific embodiment the invention provides a control valve, the valve comprising a housing containing a passageway between an inlet and an outlet of the valve, a closure member movable in the passageway from a first position in which the valve is fully closed to a second position in which the valve is fully open, the closure member carrying a seal to engage the wall of the passageway to seal the passageway, the wall of the passageway defining at least one groove, the groove being located in the passageway wall downstream of the engagement between the wall and the seal in said first position, the groove having a transverse cross-section that increases in area in the downstream direction, whereby movement of the closure member from the first position towards the second position opens a flow channel through the groove.
As indicated above, the valves of the invention are particularly useful for incorporation into the dispense head of a beverage dispenser where they may be used to control the flow of fluids to be mixed at the dispense valve, e.g. syrup and carbonated water, or they may be incorporated into a coolant manifold for use in cooled beverage dispense systems. A typical manifold may contain a plurality of valves controlling outlets for the coolant, the valves being spaced along a common manifold. Each valve may comprise a housing containing a passageway from the common manifold to the valve outlet.
In a typical coolant manifold, the passageway of each control valve in the manifold will usually comprise at least a portion in the form of a right cylinder, and the closure member will be a corresponding cylinder of outside diameter slightly less than the internal diameter of the passageway, the closure member having an xe2x80x9cOxe2x80x9d-ring seal attached around its outer surface to seal against the passageway wall. In such an arrangement, the grooves may be, for example, a pair of tapering V-shaped grooves opposed across the right cylinder, the cross-section of each groove increasing, for example, in the downstream direction. The grooves may, of course, have a different tapering cross-section, e.g. of generally circular, rectangular or other shape, but for convenience the invention will be more specifically described below with reference to the use of V-grooves although it will be appreciated that it is not intended to be limited thereto.
Depending on the desired particular construction, the V groove or grooves in the passageway may increase in cross-sectional area in the upstream or downstream direction. In the latter case, the valves have the added advantage of having greater self-cleaning properties, i.e. larger particles can pass more readily through the valve in the open position without causing partial blockage than for a conventional valve having an annular passageway of the same throughput.
When a conventional valve is used in a partially open position, i.e. between the above-mentioned first and second positions, it will be appreciated that the partially open passageway, in the case of a tapering cylindrical passageway, is a narrow annular passageway between the wall and the closure member. In the absence of the groove(s) of the invention, dirt particles can get trapped in this narrow annular passageway and thereby partially block the passageway and reduce the desired throughflow of, e.g. coolant. However, the presence of the groove(s) of appropriate and increasing cross-sectional area to provide the desired flow rates at different valve openings, enables dirt particles that would otherwise have been trapped to flow through the groove(s) leaving the valve unblocked and the rate of flow at the required level. As the valve opening is gradually increased to full, the increasing cross-sectional area of the groove(s) enables a dirt particle of a particular size to pass through sooner than it would otherwise have done or, at any given partial opening of the valve, grit particles of larger size can pass through than could have done so in a conventional arrangement without the grooves. The valve can conveniently be flushed to remove any trapped particles by fully opening it.
As indicated above, conveniently the passageway and closure member are of generally cylindrical transverse cross-section and a pair of grooves may be opposed diametrically across the passageway. However, it will be appreciated that the invention is not limited to such constructions.
Where more than one groove is provided in the passageway, it is not essential that all the grooves are positioned to commence and finish at the same distance along the passageway.
The progressive increase or decrease in area of the groove flow channels can provide excellent linear flow through valves of the invention.